Reconfiguration of address space based on loading short pointer mode application

ABSTRACT

A short pointer mode application has been loaded. Based on determining that the short pointer mode application has been loaded, an address space configured for a long pointer mode environment is reconfigured. The address space has one portion addressable by short pointers of a defined size and another portion addressable by long pointers of another defined size, and the reconfiguring includes obtaining a long pointer library, and loading the long pointer library in the one portion of the address space addressable by short pointers.

BACKGROUND

One or more aspects relate, in general, to processing within a computingenvironment, and in particular, to processing associated with long andshort pointers.

Many architectures, including the z/Architecture and Power architectureoffered by International Business Machines Corporation, Armonk, N.Y.,offer multiple Application Binary Interface (ABI) environments. Forinstance, the z/Architecture environment ships a 31-bit (31b)environment in addition to a 64-bit (64b) environment. Similarly, POWERships 32-bit (32b) and 64-bit (64b) environments. These environments areimplemented by a multi-library (multilib) approach, in which multiplelibraries, middleware and build tools are provided, one for eachenvironment, that all refer to the same system functions. Otherarchitectures similarly provide a multilib approach.

In each environment, pointers are used to reference objects. Forinstance, in 31-bit or 32-bit environments, short pointers (e.g., 31b or32b pointers) are used which contain offsets to objects local to itsprocesses. Similarly, in 64-bit environments, long pointers (e.g., 64bpointers) are used that point to objects that may be outside the currentaddress space.

Development and distribution of multiple system libraries increasesdeveloper maintenance, as well as build and debug costs, and increasesthe support that is to be provided to subsystems that are shipped.

SUMMARY

Shortcomings of the prior art are overcome and additional advantages areprovided through the provision of a computer program product forfacilitating processing in a computing environment. The computer programproduct comprises a storage medium readable by a processing circuit andstoring instructions for execution by the processing circuit forperforming a method. The method includes, for instance, determining thata short pointer mode application has been loaded; and reconfiguring,based on determining the short pointer mode application has been loaded,an address space configured for a long pointer mode environment, theaddress space having one portion addressable by short pointers of adefined size and another portion addressable by long pointers of anotherdefined size, the reconfiguring including: obtaining a long pointerlibrary; and loading the long pointer library in the one portion of theaddress space addressable by short pointers. The reconfiguringfacilitates execution of a short pointer mode application in a longpointer mode environment.

As an example, the determining of the whether a short pointer modeapplication has been loaded includes checking a field associated with ofthe application.

In one example, the defined size of the one portion of the address spaceis 31 bits or 32 bits, and the other defined size of the other portionof the address space is 64 bits.

In one embodiment, the short pointer mode application is loaded in theone portion of the address space addressable by short pointers.

Further, in another embodiment, the reconfiguring includes configuring astack in the one portion of the address space addressable by shortpointers.

In yet another embodiment, the reconfiguring further includesconfiguring a heap in the one portion of the address space addressableby short pointers.

In one aspect, a select library to load is obtained, and a determinationis made as to whether the select library is a short pointer library.Based on the select library being a short pointer library, the selectlibrary is loaded in the one portion of the address space addressable byshort pointers.

Further, based on the select library not being a short pointer library,the select library is loaded in the other portion of the address space.

In a further aspect, the select library is loaded in the one portion ofthe address space or the other portion of the address space, based onthe select library not being a short pointer library; and the selectlibrary modifies one or more characteristics of the select library forthe select library to be operable in a short mode environment.

In one example, a pointer of the long pointer library is a procedurelinkage table pointer, and the procedure linkage table pointer is a longpointer.

Methods and systems relating to one or more aspects are also describedand claimed herein. Further, services relating to one or more aspectsare also described and may be claimed herein.

Additional features and advantages are realized through the techniquesdescribed herein. Other embodiments and aspects are described in detailherein and are considered a part of the claimed aspects.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more aspects are particularly pointed out and distinctly claimedas examples in the claims at the conclusion of the specification. Theforegoing and objects, features, and advantages of one or more aspectsare apparent from the following detailed description taken inconjunction with the accompanying drawings in which:

FIG. 1 depicts one example of a computing environment to incorporate anduse one or more aspects of the present invention;

FIG. 2 depicts one example of an application compilation process, inaccordance with an aspect of the present invention;

FIG. 3 depicts one example of logic to allocate memory and/or a registerfor a short pointer, in accordance with an aspect of the presentinvention;

FIG. 4A depicts one example of logic to convert pointer load and storeinstructions to load-short-and-zero and store short instructions, inaccordance with an aspect of the present invention;

FIG. 4B depicts one example of a Load Logical instruction used inaccordance with an aspect of the present invention;

FIG. 4C depicts one example of a Store instruction used in accordancewith an aspect of the present invention;

FIG. 5 depicts one example of logic to translate pointer computations,in accordance with an aspect of the present invention;

FIG. 6 depicts one example of logic to pass short pointers to parametersin a zero extended long format, in accordance with an aspect of thepresent invention;

FIG. 7 depicts one example of logic to receive long pointers from calledfunctions and use as short pointers, in accordance with an aspect of thepresent invention;

FIG. 8 depicts one example of logic to manage shared pointers, inaccordance with an aspect of the present invention;

FIG. 9 depicts one example of logic to handle shared in-memory pointers,in accordance with an aspect of the present invention;

FIG. 10 depicts one example of a memory address space layout, inaccordance with an aspect of the present invention;

FIG. 11 depicts another example of a memory address space layout, inaccordance with an aspect of the present invention;

FIG. 12 depicts one example of logic to determine how to perform loadand configuration, in accordance with an aspect of the presentinvention;

FIG. 13 depicts one embodiment of logic to perform load andconfiguration in a short pointer address space, in accordance with anaspect of the present invention;

FIG. 14 depicts another embodiment of logic to perform load andconfiguration in a short pointer address space, in accordance with anaspect of the present invention;

FIG. 15 depicts one example of logic to determine the execution mode, inaccordance with an aspect of the preset invention;

FIG. 16 depicts one embodiment of logic relating to loading pointers inmemory, in accordance with an aspect of the present invention;

FIGS. 17A-17B depict further details relating to processing of shortpointer mode applications, in accordance with an aspect of the presentinvention;

FIG. 18A depicts another example of a computing environment toincorporate and use one or more aspects of the present invention;

FIG. 18B depicts further details of the memory of FIG. 18A, inaccordance with an aspect of the present invention;

FIG. 19 depicts one embodiment of a cloud computing node;

FIG. 20 depicts one embodiment of a cloud computing environment; and

FIG. 21 depicts one example of abstraction model layers.

DETAILED DESCRIPTION

In accordance with one or more aspects, a capability is provided toenable short pointer mode applications (i.e., applications that useshort pointers) to execute in a long pointer mode environment. Shortpointers are of one size (e.g., 31b or 32b) and long pointers are ofanother size (e.g., 64b), different from the one size.

As indicated above, development and distribution of multiple systemlibraries increases developer maintenance, build and debug costs, aswell as increases support that is to be provided to subsystems that areshipped. In an attempt to address this, interposer libraries have beenused to bridge between differences in interfaces, e.g., by translatingfrom one size of data (e.g., pointers) to another size of data. However,the interposer libraries simply replace one set of libraries that needsto be built, debugged and maintained distinctly for a short pointer modeenvironment with another set of libraries that needs to be written,built, debugged and maintained. Therefore, a capability is needed toreduce the number of build environments provided, e.g., such that, inone aspect, a single environment and library set is distributed for eacharchitecture, while retaining the advantages of short pointer modes andwithout the need to build another set of libraries, including interposerlibraries.

One embodiment of a computing environment to incorporate and use one ormore aspects of the present invention is described with reference toFIG. 1. In one example, the computing environment is based on thez/Architecture, offered by International Business Machines Corporation,Armonk, N.Y. One embodiment of the z/Architecture is described in“z/Architecture Principles of Operation,” IBM Publication No.SA22-7832-10, March 2015, which is hereby incorporated herein byreference in its entirety. Z/ARCHITECTURE is a registered trademark ofInternational Business Machines Corporation, Armonk, N.Y., USA.

In another example, the computing environment is based on the PowerArchitecture, offered by International Business Machines Corporation,Armonk, N.Y. One embodiment of the Power Architecture is described in“Power ISA™ Version 2.07B,” International Business Machines Corporation,Apr. 9, 2015, which is hereby incorporated herein by reference in itsentirety. POWER ARCHITECTURE is a registered trademark of InternationalBusiness Machines Corporation, Armonk, N.Y., USA.

The computing environment may also be based on other architectures,including, but not limited to, the Intel x86 architectures. Otherexamples also exist.

Referring to FIG. 1, in one example, a computing environment 100includes at least one central processing unit (CPU) 102 (a.k.a., aprocessor) coupled to one or more levels of caches 125. Centralprocessing unit 102 includes, for instance, one or more execution units104 to request and consume data. Execution units 104 are coupled to aload/store unit (LSU) 108, which includes a load/store queue (LSQ) 110.Load/store unit 108 issues memory access operations (loads and stores)that retrieve prefetched data or cause the data to be fetched from thememory subsystem. LSU 108 may be coupled to a data cache 114 via, e.g.,a translation mechanism 112, indicated as, e.g., a translationlook-aside buffer (TLB) or an effective to real address translationtable (ERAT).

Further CPU 102 may execute a compiler 120 to compile programs, and thecompiler may use short pointer logic 122, as described herein, tofacilitate processing of short pointer mode applications in a longpointer mode environment. Additionally, other modules or managersexecuting on the CPU, such as a library manager, may implement shortpointer processing 150.

CPU 102 is coupled to and communicates with a memory hierarchy thatincludes, for instance, data cache 114, which is an L1 data cache; oneor more other level caches 125, which may include a single level two(L2) cache or multiple other sequentially numbered levels, e.g., L3, L4;a memory 130; and an associated memory controller 127, which controlsaccesses to memory 130. L1 data cache 114 serves as a prefetch bufferfor data (and/or data streams) that are prefetched. L1 data cache has acorresponding load miss queue (LMQ) 116, which the cache utilizes tosave information about ongoing prefetch requests.

In addition to the example memory hierarchy, computing environment 100may also include additional storage devices that form a part of thememory hierarchy from the perspective of CPU 102. The storage devicesmay be one or more electronic storage media, such as a floppy disk, harddrive, CD-ROM, or DVD. CPU 102 communicates with each of the abovedevices within the memory hierarchy by various mechanisms, including viabuses and/or direct channels, as examples.

In accordance with an aspect of the present invention, a short pointermode (a.k.a., short mode) application executes in a long pointer mode(a.k.a., long mode) environment. The application uses, for instance,31-bit or 32-bit pointers. When the application calls a function, itpasses pointers in a zero extended manner in, for instance, a longregister (e.g., a 64-bit register). The short data (e.g., 31-bit or32-bit data) is loaded in a long (e.g., 64-bit) register at no extracost as long data. In one example, this is accomplished using a loadlogical instruction, as described herein. The low order bits of anapplication pointer correspond to those bits used by the short pointer.

In one aspect, in order for a short mode application to execute in along mode environment, a compilation process is performed, in accordancewith an aspect of the present invention. One embodiment of thiscompilation process is described with reference to FIG. 2, and isperformed by, e.g., compiler 120 executing on processor 102.

Referring to FIG. 2, the compiler receives source code of an applicationto be compiled, as well as an indication that the application is a shortmode application that is to be executed in a long mode environment, STEP200. The compiler reads the application and translates it into aninternal representation (IR), as is known, STEP 202. Further, for eachin-memory pointer in the application, the compiler allocates an amountof memory for the pointer that is the size of a short pointer; and foreach register pointer, the compiler provides a full size register (e.g.,64-bits) for the short pointer, STEP 204. For instance, for a 32-bitin-memory pointer, the compiler allocates 32 bits of memory, but for a32-bit register pointer, a 64-bit register is provided.

Additionally, load and store instructions that typically load or storedata in a long mode (e.g., 64b) are converted to load-short-and-zero andstore-short instructions, respectively, STEP 206. In particular, thecompiler replaces, e.g., the load instruction with a load-short-and zeroinstruction (e.g., referred to as load logical in the z/Architecture).In one example, the load-short-and-zero instruction includes a load zeroextending data instruction, in which data in a short mode (e.g., 31b or32b) is loaded into the register, and then zeros are appended to providelong mode data (e.g., 64 bits). In another embodiment, aload-short-and-sign-extend instruction may be used.

Further, in one example, the compiler replaces, e.g., a store relativelong instruction with a store-short instruction (which in, for instance,the z/Architecture is a Store instruction). The store-short instructionstores low order bits of a register, in which data in a short mode(e.g., 31b or 32b) is stored to memory while high order bits areignored. In other embodiments, store-short instructions may be used toensure that no significant bits are dropped, e.g., by ensuring thatignored high order bits are, for example, one of an extended sign bitand/or a zero bit. In one or more of the embodiments, special pointerconversion instructions are not used, simplifying the Instruction SetArchitecture (ISA) that is employed. Instead, load and storeinstructions typically provided in the ISA may be used.

Optionally, the compiler may translate pointer computations to includeoverflow handling when a short pointer computation may generate anoverflow, STEP 208, as described below.

Additionally, short pointers are passed as parameters in theirzero-extended long format to use long format service functions, STEP210. For instance, register parameters are automatically passed in thelong format, and in-memory pointer parameters are passed using, forinstance, load and store instructions that load or access a long pointerrepresentation in a parameter list holding an image of the long formregister representation of a parameter.

In one example, short pointer computations are maintained in registersin a zero-extended long format, such that they represent a memory accessaddress usable with long pointer memory access instructions, e.g., inaccordance with an address space layout for a short mode application ina long mode environment, in accordance with an aspect of the presentinvention.

Moreover, long pointers may be received from called functions and areused as short pointers, STEP 212. This relies on configuring the addressspaces and environment to ensure long pointers are returned that arealso valid short pointers.

Further details regarding various of the processes described above forthe compilation technique are described with reference to FIGS. 3-7. Thelogic of each of the figures is performed by, e.g., compiler 120executing on the processor, in one example.

Referring to FIG. 3, further details regarding allocation of memoryand/or registers for short pointers are described. Initially, thecompiler receives a pointer for which allocation is to be performed,STEP 300. A determination is made as to whether the pointer is to beallocated in memory or in a register (e.g., in a central processingunit), INQUIRY 302. If memory is to be allocated for the pointer, thenan amount of memory is allocated for a short pointer (e.g., 31 or 32bits), STEP 304. However, if a register is to be allocated for thepointer, then a full register (e.g., 64-bit register) is allocated forthe pointer, STEP 306. In this example, the short pointer when placed inthe register will be appended with zeros (e.g., the first 33 or 32 bitswill be zeros, depending on whether the short pointer is 31 or 32 bits).This process is performed for each pointer received by the compiler.

Further details regarding converting pointer load and/or storeinstructions are described with reference to FIG. 4A. Initially, arequest is received to generate code for a pointer move in accordancewith a compiler-based code generation from the source code and/or aninternal compiler representation thereof, STEP 400. A determination ismade as to whether the pointer is being moved between registers orbetween a register and memory, INQUIRY 402. If the pointer is beingmoved between registers (REG/REG), then the pointer is copied to thefull register previously allocated, STEP 404. However, if the pointer isto be moved between a register and memory (REG/MEM), then a furtherdetermination is made as to whether the pointer is being moved to memoryor from memory, INQUIRY 406. If the pointer is being moved from memory,then, in one example, a load short and zero extend instruction is used,STEP 408. In particular, the pointer is stored in the register, and thenthe remaining positions of the register are filled with zeros.

One example of a load short and zero extend instruction is the LoadLogical instruction defined in the z/Architecture, an example of whichis depicted in FIG. 4B. As shown, in one example, a Load Logicalinstruction 450 includes an opcode field 452 used to provide anoperation code that indicates a load logical operation; a first registerfield (R₁) 454; and a second register field (R₂) 456.

In operation, the contents of the register designated by R₁ field 454are stored unchanged at the second operand address. The contents of theregister designated by R₂ field 456 specify the second operand address.

Returning to INQUIRY 406 of FIG. 4A, if the pointer is being moved tomemory, then, in one example, a store instruction is used to store theshort (low order portion) in memory, STEP 410. One example of astore-short instruction is the Store instruction defined in thez/Architecture, an example of which is depicted in FIG. 4C. As shown, inone example, a Store instruction 470 includes an opcode field 472 usedto provide an operation code that indicates a store short operation(e.g., stores 32 low order bits); a register field (R₁) 474; an indexfield (X₂) 476; a base field (B₂) 478; and a displacement field (D₂)480.

In operation, the first operand (e.g., contents of the registerspecified in R₁) is placed unchanged at the second operand location,defined by X₂, B₂ and D₂. For instance, the contents of the generalregisters designated by the X₂ and B₂ fields are added to the contentsof the D₂ field to provide an address (i.e., the second operandlocation).

Referring to FIG. 5, further details regarding pointer arithmetic aredescribed. Initially, the compiler receives a short pointer computationfor which code is to be generated, STEP 500. A determination is made asto whether the short pointer arithmetic can overflow (and, in oneembodiment, cannot be handled by address mirroring), INQUIRY 502. Forinstance, in one embodiment, a portion of an address space is mirrored.As an example, this is an entire 32b address space below and/or abovethe short pointer area, as described below. In other embodiments, thisis only a portion thereof. When an address computation is performed thatmay overflow, but falls within the mirrored range, no overflow handlingis necessary. In one embodiment, a check of whether address mirroringmay handle an overflow is performed by testing for an add or a subtractof a value that is smaller than the mirrored region—either because theconstant is known, or a range of a value is known, e.g., a data size.Thus, for example, when a byte is added to an address, an overflow of nomore than 255 bytes can occur, so if at least 255 bytes are mirrored,then mirroring can be determined to handle an address overflow.

If the arithmetic can overflow, then code is included to mask theoverflow and maintain wrap around, STEP 504. For instance, the codeensures that the short pointer stays within a short pointer addressspace, as described below. However, if the short pointer arithmetic isnot to overflow, the pointer arithmetic is generated without overflowhandling, STEP 506.

Referring to FIG. 6, further details regarding passing short pointers asparameters in long pointer mode are described. Initially, a shortpointer is received for parameter passing, STEP 600. The appropriateparameters are allocated and passed, in accordance with a long pointerABI, STEP 602. For instance, a determination is made as to whether theparameter value is to be passed in memory, INQUIRY 604. If it is not tobe passed in memory, but instead, in a register, then a full register isallocated for the pointer, as described above, STEP 606. Otherwise, ifthe parameter is to be passed in memory, the memory is allocated for along pointer and the long pointer is stored in the allocated memory, inaccordance with a long pointer ABI, STEP 608. This enables the use oflong format service functions, even though the pointers are shortpointers.

In addition to the above in which short pointers are passed asparameters and used as long pointers, long pointers may be received fromcalled functions and used as short pointers, as described further withreference to FIG. 7. Initially, results are received as a long value,STEP 700. A determination is made as to whether the value was passed inmemory, INQUIRY 702. If the value was passed in a register parameter,then the pointer is a zero extended long pointer in accordance withregister representations for short pointers, STEP 704. Otherwise, if thevalue was passed as a memory parameter, then either the long value isloaded into a register using a long register access or using load shortand zero, optionally with an adjusted address, STEP 706.

As described above, values may be in a long mode or a short mode and maybe stored in memory or registers. The storage in memory depends on thetype of storage format for a particular architecture. For instance, thez/Architecture uses a Big-Endian format and the POWER architecture usesa Little-Endian format. Examples of storage of long and short values inmemory and registers for the different formats are depicted below:

For a long value access:

-   -   In the Big-Endian format the value in memory is:        0x00000000VARIABLE;        -   Load instruction transmits all bytes.    -   In the Big-Endian format, the value in a register is:        0x00000000VARIABLE.

For a long value access:

-   -   In the Little-Endian format the value in memory is:        0xLEABRIVA00000000;        -   Load instruction transmits all bytes.    -   In the Little-Endian format, the value in a register is:        0x00000000VARIABLE.

For a short value access:

-   -   In the Big-Endian format, the value in memory is:        0x00000000VARIABLE;        -   Load instruction transmits short pointer and extends from            adjusted address (skip zeros).    -   In the Big-Endian format, the value in a register is:        0x00000000VARIABLE.        -   Zero extended.

For a short value access:

-   -   In the Little-Endian format the value in memory is:        0xLEABRIVA00000000;        -   Load instruction transmits short pointer, and extends.    -   In the Little-Endian format, the value in a register is:        0x00000000VARIABLE.        -   Zero extended.

In accordance with a further aspect, a check of the high order bits isperformed to ensure they are an expected value (e.g., zeros). Inparticular, when a pointer is returned, only the low order bits areused. Therefore, in one embodiment, a check is made to ensure that thehigh order bits are zero (or another selected value), corresponding tothe selected mapping. In one embodiment, sign extension is used, and thehardware is equipped to recognize when data extends across the0x80000000 boundary, e.g., by making memory above 0x80000000inaccessible to induce errors for common incorrect accesses. In oneembodiment, an entire range of 2 GB is inaccessible, until 0xFFFFFFFF.This may be accomplished by configuring the address space by not makingany storage accessible via page table entries.

As described herein, some pointers are represented as 64 bits. Thus,long pointers are written by writing zero-extended (or otherwiseextended) short pointers, and are read by reading the bytescorresponding to short pointers. In one embodiment, high bytes arechecked to be zero (or sign copies).

In a further aspect, pointers may be shared between long and shortpointer code. For example, a pointer may be shared with a library inmemory and that library is defined in long mode, and therefore, expectsa long mode pointer. However, it has been defined, in accordance with anaspect of the present invention, the pointers should be short pointers.Therefore, in accordance with a further aspect, the pointer is definedas a shared pointer to be shared with a library, and action is takenbased thereon.

One embodiment of logic used to share pointers with a library isdescribed with reference to FIG. 8. In one example, this logic isperformed by the compiler (e.g., compiler 120).

Referring to FIG. 8, a pointer in short pointer mode is received, STEP800. A determination is made as to whether the pointer is to be used asa private pointer in a short pointer binary or as a shared pointer witha long pointer binary, STEP 802. That is, is the short mode pointer tobe shared with a long mode library in memory. In one embodiment, this isdetermined by an indication that is provided to indicate how the pointeris to be used. If it is a pointer to be shared with a library, INQUIRY804, then sharing actions are performed, STEP 806. Otherwise, thepointer is not shared with a library and sharing actions are notperformed, STEP 808. Further details regarding sharing are providedbelow.

In accordance with an aspect of the present invention, there are variousoptions for handling shared pointers, including permitting the sharingor preventing it. In one option, a function may be marked as being notcross-resolvable to a 64b system library so that at runtime, a suitableinterception may occur. This is performed by, for instance, storinginformation in a symbol table to preclude such cross-linking. In anotherexample, a symbol name is modified, e.g., by appending short. In oneembodiment, a library might selectively export a second function adaptedto process short pointers passed by reference.

Examples of standard functions that receive such a pointer are thefollowing stdio functions found, e.g., in zLinux:

-   -   stdio.h:extern FILE *open_memstream (char**_bufloc,        size_t*_sizeloc)_THROW_wur;    -   stdio.h:extern int vasprintf (char**_restrict_ptr,_const        char*_restrict_f);    -   stdio.h:extern int—asprintf (char**_restrict_ptr);    -   stdio.h:extern int asprintf (char**_restric_ptr);    -   stdio.h:extern_IO_ssize_t_getdelim (char**_restrict_lineptr);    -   stdio.h:extern_IO_ssize_t getdelim (char**_restrict_lineptr);    -   stdio.h:extern_IO_ssize_t getline (char**_restrict_lineptr).

The above described option includes detecting and preventing sharingwhen there is a pointer size mismatch that manifests itself whenpointers are shared in memory (other than as a pointer specified as afunction call parameter when parameter registers have been exhausted).The user/loader is to provide separate short pointer libraries forlibraries that share more than pointers in the function calls. Eitherglobal pointer variables, or records/structs/classes/unions or otheraggregates containing pointers are provided. With this option ofpreventing sharing, an indication is provided that the environment isnot adapted to resolve the situation and an error is raised.

In a further option, pointer data is to be shared with a library otherthan as input or output parameters specified in a function call, e.g.,as a value allocated in memory or as a structure passed as a parameter.In one embodiment, this is handled between code generation andenvironment configuration. As an example, a short pointer binaryrecognizes when a pointer is shared, and writes a long pointer bywriting it in its zero-extended form or reading it in its zero extendedform. In accordance with an aspect of the present invention, theenvironment is configured such that a long function only generatespointers that are also valid as short pointers. This is not cognizant tothe long pointer library which is generated as long pointer code withoutany allowance for handling short pointers. This is accomplished byhaving the long pointer library work on long pointers, but allocatingstorage so the memory locations can be represented as valid shortpointers.

One embodiment of logic to share in-memory pointers between short andlong pointer binaries is described with reference to FIG. 9. Initially,a pointer is received in a short pointer compilation, STEP 900. Adetermination is made as to whether the pointer is to be a privatepointer in a short pointer binary or a shared pointer with a longpointer binary, STEP 902. If it is a shared pointer, INQUIRY 904, thenmemory is allocated for the shared pointer as a long pointer (e.g., 64bits in memory are allocated), STEP 906. The pointer is written as azero-extended long pointer and read as a long pointer, STEP 908.

However, if the pointer is not a shared pointer, INQUIRY 904, thenmemory for the private pointer is allocated as a short pointer (e.g., 32bits in memory are allocated), STEP 910. The pointer is loaded andstored as a short pointer, STEP 912.

To facilitate executing short mode applications in a long modeenvironment, memory address spaces are configured in particularconfigurations, in accordance with an aspect of the present invention.As depicted in FIG. 10, a memory address space 1000 is a long pointeraddress space 1004 that includes addresses 0x00000000_00000000 to0xFFFFFFFF_FFFFFFFF. Short pointer address space 1002 is implemented ina first portion (e.g., the first 4 GB (gigabytes)) of the long pointeraddress space. As such, addresses 0x00000000_00000000 to0x00000000_FFFFFFFF are addressable by short pointers.

With this configuration, short pointers may be converted to longpointers by zero extending from memory. For instance, the compilergenerates code to perform the conversion, and during execution(runtime), the conversion is performed (i.e., the actual data isconverted). Thus, during execution of a short pointer mode applicationloaded in an address space (e.g., the first portion of the addressspace), one or more short pointers of the short pointer mode applicationare converted to one or more long pointers, and the one or more longpointers are used to access memory within, e.g., the first portion ofthe address space addressable by short pointers. In one example, aninstruction to access the memory typically accesses the long pointeraddress space, but because the pointer has been converted from a shortpointer, it will access the first portion of the address space.

In a further aspect, the memory space configuration may handle wraparound situations for the short pointer address space, as shown in FIG.11. For instance, when one is added to the largest number, the resultrolls over and starts again at the bottom. To manage this, a shadowsection of memory 1100 is configured above the first portion 1002 ofmemory. This is configured, in one example, as the same size as thefirst portion.

With this aspect, libraries specific to short pointer applications, ifany, are loaded into the range of addresses corresponding to the shortaddresses. Further, long pointer libraries are also loaded into thisregion, meaning all references that the library naturally has to itsdata and text are representable as short pointers, even if representedas long pointers.

In accordance with aspects of compiling a binary (i.e., an application)for short pointer mode, additional actions may be performed to ensureenhanced addressability. In one example, when library data structuresare used by an application, additional steps may be taken. For example,a library may define an extern (i.e., global) pointer variable that isto be updated by a user application. As such, all bytes of a longpointer may be updated (in particular for the Big-Endian environment,although even in Little-Endian environments where the low-order bytes ofa long pointer coincide with a short pointer in their entirety, anexplicit clearing of the remaining bytes may be performed).

Examples of such global pointers include:

-   -   stdio.h:extern struct_IO_FILE *stdin;    -   stdio.h:extern struct_IO_FILE *stdout;    -   stdio.h:extern struct_IO_FILE *stderr;    -   time.h:extern char *_tzname[2];    -   time.h:extern char *tzname[2];    -   unistd.h:extern char **_environ;    -   unistd.h:extern char **environ;    -   zutil.h:extern const char *const z_errmsg[10].

Also, a library may define aggregate data types containing pointers. Inthose cases, a user executable is to adhere to a data layout thatassigns a number of bytes that is commensurate with the long pointers(so as to keep offsets of subsequent aggregate members consistentbetween a long pointer library and a short pointer executable). Thepointers are to be initialized correctly to place a short pointer at thecorresponding long pointer location (this is implicit for aLittle-Endian architecture, but a ‘shift’ is performed for a Big-Endianarchitecture, such as z/Architecture).

One example includes:

-   -   bits/pthreadtypes.h:    -   typedef struct_pthread_internal_list    -   {    -   struct_pthread_internal_list *_prev;    -   struct_pthread_internal_list *_next;    -   }_pthread_list_t;

In a short pointer program generation technique, some pointers areidentified as long pointers. They are updated as a long pointer (e.g.,zero-extended) reflecting the positioning of the short pointerenvironment in the long pointer environment (e.g., low 4 GB of theaddress space).

In accordance with one compiler embodiment, this may be accomplished byspecifying an attribute:

-   -   typedef struc_pthread_internal_list    -   {    -   struct_pthread_internal_list *_prev_attribute_(long);    -   struct_pthread_internal_list *_next_attribute_(long);    -   }_pthread_list_t;

In another embodiment, this may be accomplished by scoping, e.g., usingan extern grouping mechanism, such as extern property { . . . }.

This allows multiple data objects and data types to be modified:

-   -   extern “long” {    -   extern struct_IO_FILE *stdin;    -   extern struct_IO_FILE *stdout;    -   extern struct_IO_FILE *stderr;    -   typedef struct_pthread_internal_list    -   {    -   struct_pthread_internal_list *_prev_attribute_(long);    -   struct_pthread_internal_list *_next_attribute_(long);    -   }_pthread_list_t;    -   }

This scoping may be used in conjunction with preprocessor directives toupdate a set of header files in their entirety while enabling them tostay operable as long pointer mode headers for unmodified and unenabledcode generators (e.g., compilers), for example, in conjunction withignoring the header in an almost completely unmodified compiler equippedto ignore such directives, or in a completely unmodified compiler inconjunction using preprocessor commands, e.g., as follows:

-   -   #ifdef_short_pointer_mode    -   extern “long” {    -   #endif    -   extern struct_IO_FILE *stdin;    -   extern struct_IO_FILE *stdout;    -   extern struct_IO_FILE *stderr;    -   typedef struct_pthread_internal_list    -   {    -   struct_pthread_internal_list *_prev_attribute_(long);    -   struct_pthread_internal_list *_next_attribute_(long);    -   }_pthread_list_t:    -   #ifdef_short_pointer_mode    -   }    -   #endif

In a further example, completely unmodified source text may beinterpreted by specifying their individual filename, or entiredirectories as being subject to interpretation as long pointer modescope, as a compiler command line parameter, as a compiler configurationfile, and/or hard coded in the compiler program logic.

Short pointers are converted to long pointers by, for instance, zeroextending (or otherwise modifying the pointer to locate it in the propersubspace of the address space). In a further example, short pointers areconverted to long pointers by sign extension. Other possibilities alsoexist.

Long pointers are converted to short pointers, in at least oneembodiment, by ignoring additional bits. This conversion is, e.g.,automatically performed by the compiler absent intervention of adeveloper/user. In another embodiment, an explicit check is performedfor data conversion to ensure that data is within the short pointeraddressing range.

As yet a further example, long type information may be similarly handledas long pointer information, e.g., the long data type may be representedas a 32b quantity, except when in a long data mode. In one embodiment,long/short data and long/short pointer mode are separately selectable.In another embodiment, they are linked.

In another example, when multiple declarations are present, some with along attribute and others without the long attribute, a long attributeis chosen and no error is issued, when the long attribute is detectedbefore the first use of a declaration that has resulted in tangible andirrevocable decisions (e.g., allocating a variable with a shorter datasize, or generating code making reference to the layout). In anotherembodiment, one of a warning and an error is generated.

In one or more aspects, an application address space is configured so asto enable execution of short pointer mode applications in conjunctionwith long pointer libraries. In another aspect, a short pointer modeapplication is also enabled to load a short pointer mode library. (Inanother aspect, when a long pointer mode application attempts to load ashort pointer mode library, the application is terminated and an erroris issued.) In accordance with one embodiment, when an applicationidentified as a short pointer mode application is loaded, its addressspace is configured so as to allow it to operate safely with a shortpointer representation, and without providing a full set of shortpointer libraries.

In one embodiment, the system interpreter (i.e., the system componentresponsible for loading the application, e.g., ld.so) is configured toload 32b and 64b applications. In one embodiment, a single ld.socomponent is so enabled. In another embodiment, a system interpreterld.so recognizes when a short pointer mode application is to be loaded,and initializes a short pointer application loader. In one embodiment,this may be recognized with a magic number in a program executableformat indicating the application type. In another embodiment, thesystem interpreter may be specified using a sequence enabling thespecification of an application interpreter, e.g., “#!/sbin/ld.so31” or“#!/sbin/ld.so32”, as examples.

In one embodiment, a portion of the work of the short pointer loader isincluded in libcrt.o, or another startup module linked with the mainexecutable, or loaded as a shared library. In accordance with such anarchitecture, such a component is equipped to reconfigure at least someaspects of a long pointer address space to a short pointer addressspace, based on loading a short pointer mode application, in accordancewith an aspect of the present invention. With this reconfiguration,characteristics of an initialized 64b address space are modified toconform to characteristics described herein. (E.g., in one aspect, anapplication stack may be moved from a high memory location above the0x00000000_FFFFFFFF address to a location below this address.)

One embodiment of logic to load and configure an application addressspace for use by short mode applications in conjunction with longpointer mode libraries is described with reference to FIG. 12.Initially, a determination is made as to whether the application beingexecuted uses long pointers or short pointers, STEP 1200. This isdetermined based on, for instance, a field associated with theapplication. If the application uses long pointers, INQUIRY 1202,conventional load and configuration processing is performed, STEP 1204.Otherwise, load and configuration processing, in accordance with aspectsof the present invention, is performed, STEP 1206, as described below.

Referring to FIG. 13, initially, the application binary is loaded in theshort pointer address space, STEP 1300. For instance, based on aninvocation of an application program compiled in short pointer mode, theshort pointer loader loads the application into the low 4 GB (or thememory range that corresponds to the short pointer memory range),ensuring that all data structures within a short pointer application canbe accessed via short pointers, e.g., 32b pointers. Based on theconfiguration, the loader also loads the libraries (e.g., long pointerlibraries) in the short pointer address space, STEP 1302. The librariesare, for instance, long pointer libraries referenced by long pointers.In one particular example, a long pointer of a long pointer library is aprocedure linkage table pointer.

As is known, a procedure linkage table converts position-independentfunction calls to absolute locations. The link-editor cannot resolveexecution transfers such as function calls between different dynamicobjects. So, the link-editor arranges to have the program transfercontrol to entries in the procedure linkage table. The runtime linkerthus redirects the entries without compromising the position-independentand shareability of the program's text. Executable files and sharedobject files have, e.g., separate procedure linkage tables. In the casein which the long pointer is to address the portion of the address spacefor short pointer mode, then, in one example, the entry of the PLT isloaded with the zero extended pointer. In a further example, thearchitect can place some service functions (e.g., read, write, display)in the long pointer address space, leaving more address space for theshort pointer applications, and then convert the pointers to accessthose functions. Other examples also exist.

Further, a program stack is configured in the short pointer addressspace, STEP 1304. The system loader initializes the stack within theshort pointer address space (e.g., commonly within the high area of thisaddress range). In another aspect, a component working in conjunctionwith the short pointer application receives control and relocates thestack, e.g., as part of initializing the application in crt.0 or with ahardcoded first invocation in main.

Likewise, the heap is allocated in that short pointer space, STEP 1306.The system loader sets an indication provided to the heap managementlibrary to initialize the heap below the 4 GB address. In anotheraspect, a separate heap management library is provided for short pointermode programs. In accordance with the modified operation of the heaplibrary, or the separate short pointer heap library, the heap isinitialized in the short pointer memory (commonly below the allocatedapplication stack).

In one embodiment, a dynamic loader is equipped to detect environmentmismatches during linking, e.g., when a short pointer mode applicationattempts to call a function that includes a short pointer reference or apointer to a short pointer among its parameters when the function is tobe linked to a long pointer function equipped to operate on long pointerreferences to long pointers. In one embodiment, an error is generated.In another embodiment, an alternate function implementation is located,e.g., when a library may provide a select few functions adapted tohandle such references, either using a wrapper in which data conversionis performed, or with a separately compiled second version of one ormore functions fully equipped to handle short pointers. (In oneembodiment, a long pointer compiler may include an attribute for a shortpointer mode to enable the efficient writing of such code.)

In a further aspect, some libraries are provided as separate shortpointer libraries (e.g., to address pointer sharing in aggregates and/ormemory). One embodiment of logic to load and configure for suchlibraries is described with reference to FIG. 14. Initially, theapplication binary is loaded in the short pointer space, STEP 1400.Additionally, a program stack is configured in the short pointer space,STEP 1402, as well as a heap of memory, STEP 1404.

A determination is made as to the next library to load, STEP 1406, and acheck is made as to whether a short pointer version of the library isavailable, INQUIRY 1410. If a short pointer version of the library isavailable, then it is loaded, STEP 1412; otherwise, a long pointerversion of the library is loaded, STEP 1414. A further determination isthen made as to whether there are additional libraries to be loaded,INQUIRY 1416. If so, then processing continues with STEP 1406.Otherwise, processing is complete.

Additionally, in a further aspect, some libraries may be built to becognizant of executing in a 32b or a 64b environment, and thus, one ormore of the configuration, behavior, data structure use, types ofpointers returned, etc. may be adapted. For example, the memorymanagement library may change where to allocate the heap and/or the sizeof the heap; e.g., large heap in a long pointer address space, orsmaller heap in a short memory range. Other characteristics of thelibrary may also be modified to be operable in a short mode environment.

To provide adaptability, some configuration variables may be derivedfrom values set by the loader. For example, for memory management,boundaries of one or more address ranges for use in configuring a heapmay be obtained from the loader.

Alternatively, in a further embodiment, the execution mode isdetermined, and behavior is adapted based on executing different codepaths. One embodiment of logic to determine execution mode is describedwith reference to FIG. 15. Initially, a determination is made as to theexecution mode of the application, STEP 1500. If the execution mode is ashort pointer execution mode, INQUIRY 1502, then short pointercompatible behavior is provided, STEP 1504. Otherwise, long pointer modemay be taken advantage of, STEP 1506.

Further details regarding long pointer mode are described with referenceto FIG. 16. Initially, the location of the long pointer load isdetermined, STEP 1600. Further, an inquiry is made as to whether thereis an indication that short pointer interaction is available even whenloaded in long pointer memory, INQUIRY 1602. This indication may beprovided, e.g., in a header field of the library file, e.g., like theELF header or a magic number that may also be used to determine whethera module is a long pointer mode or a short pointer mode module. If shortpointer interaction is unavailable when loaded in long pointer memory,then the application is loaded in short pointer memory, STEP 1604.Otherwise, it is loaded in long pointer memory, STEP 1606.

In one aspect, some library services are provided from the long pointermemory (e.g., above 4 GB). To facilitate this, certain actions areperformed: a short pointer address space is created; long pointerlibraries are loaded into long pointer memory leaving more short pointermemory to short pointer code; a trampoline (e.g., adapting PLT(procedure linkage table) stubs) is provided for code to call a libraryin high memory, in which a short pointer mode application may call acode portion in the short pointer address space which in turn transferscontrol to code in the long pointer address space, thereby enablingshort pointer mode applications to transfer control to code in the longpointer address space without being cognizant thereof; and the memory inhigh memory code may employ more adaptation to ensure it returns onlyshort pointer data.

Described in detail is a capability for enabling short pointer modeapplications to execute in long pointer mode environments. Thiscapability includes configuring the memory space to enable short pointermode applications to be executed, loading and configuring components,such as libraries, stacks, heaps, etc., in a short pointer addressspace, and providing an application compilation process.

By building an application that can store short pointers (e.g., 31-bitor 32-bit), the cache can hold two times the number of pointers.Further, the pointers are expanded to long pointers when loaded into theCPU (e.g., zero-extended or sign-extended in register). Thus, the shortpointers may be used in a long pointer address space. As an example, a32-bit application uses 32-bit pointers but calls 64-bit libraries.

The expansion of the pointers may be used, for instance, for allpointers of the application. The expansion is performed without complexrotations and shifts, etc.

In one aspect, an application is provided, in which the entireapplication module is written to use short pointers and withoutcognizance of long pointers, while further being adapted to call alibrary written exclusively with long pointers and without cognizance ofshort pointers.

The capability includes using short pointers in a long pointer ABI, inwhich short pointers may be passed to another function withoutcognizance of whether a function being called expects short or longpointers to be provided, without support of dedicated pointer conversioninstructions, or the addition of instructions to convert a loadedpointer from a short to a long pointer.

As one example, a capability is provided to use one or more longpointer-based libraries in conjunction with short pointer code, whereinneither the calling or called module are cognizant of (or have beencompiled with cognizance of) the other module not being of the samepointer type, or calling a short-pointer module from a long pointermodule.

In one aspect, short pointers are used in a single address space, inwhich the short pointers are a compact representation for an applicationusing a portion of a single address space. Further, an application isable to have the choice of exclusively using short pointers, while alsobeing able to call library functions that were developed for longpointers.

Further details relating to processing of short pointer modeapplications are described with reference to FIGS. 17A-17B. Referring toFIG. 17A, in one embodiment, a determination is made (e.g., by checkinga field associated with the application) that a short pointer modeapplication has been loaded (1700). Based on determining the shortpointer mode application has been loaded, an address space configuredfor a long pointer mode environment is reconfigured (1702), such thatthe address space has one portion addressable by short pointers of adefined size and another portion addressable by long pointers of anotherdefined size (1704). In one example, the defined size is one of 31 bitsor 32 bits, and the other defined size is 64 bits (1706).

In one embodiment, the reconfiguring includes obtaining a long pointerlibrary (1708), and loading the long pointer library in the one portionof the address space addressable by short pointers (1710). The shortpointer mode application is loaded in the one portion of the addressspace addressable by short pointers (1712).

In one or more further embodiments, the reconfiguring includesconfiguring a stack in the one portion of the address space addressableby short pointers (1714), and/or configuring a heap in the one portionof the address space addressable by short pointers (1716).

In a further aspect, a select library to load is obtained (1718; FIG.17B), and a determination is made as to whether the select library is ashort pointer library (1720). Based on the select library being a shortpointer library, the select library is loaded in the one portion of theaddress space addressable by short pointers (1724). Further, based onthe select library not being a short pointer library, the select libraryis loaded in the other portion of the address space (1726).

In a further example, based on the select library not being a shortpointer library, the select library is loaded in the one portion of theaddress space or the other portion of the address space (1730), and theselect library modifies one or more characteristics of the selectlibrary for the select library to be operable in a short modeenvironment (1732).

As an example, a pointer of the long pointer library is a procedurelinkage table pointer, and the procedure linkage table pointer is a longpointer (1734).

In addition to the above, one or more aspects of the present inventionmay be included and used in other types of computing environments. Forinstance, another example of a computing environment to incorporate anduse one or more aspects of the present invention is described withreference to FIG. 18A. In this example, a computing environment 1800includes, for instance, a native central processing unit (CPU) 1802, amemory 1804, and one or more input/output devices and/or interfaces 1806coupled to one another via, for example, one or more buses 1808 and/orother connections. As examples, computing environment 1800 may include az Systems server, a PowerPC processor or a Power Systems server offeredby International Business Machines Corporation, Armonk, N.Y.; an HPSuperdome with Intel Itanium II processors offered by Hewlett PackardCo., Palo Alto, Calif.; and/or other machines based on architecturesoffered by International Business Machines Corporation, Hewlett Packard,Intel, Oracle, or others.

Native central processing unit 1802 includes one or more nativeregisters 1810, such as one or more general purpose registers and/or oneor more special purpose registers used during processing within theenvironment, as well a short pointer mode execution facility 1811. Theseregisters include information that represents the state of theenvironment at any particular point in time.

Moreover, native central processing unit 1802 executes instructions andcode that are stored in memory 1804. In one particular example, thecentral processing unit executes emulator code 1812 stored in memory1804. This code enables the computing environment configured in onearchitecture to emulate one or more other architectures. For instance,emulator code 1812 allows machines based on architectures other than thez/Architecture, such as PowerPC processors, Power Systems servers, HPSuperdome servers or others, to emulate the z/Architecture and toexecute software and instructions developed based on the z/Architecture.

Further details relating to emulator code 1812 are described withreference to FIG. 18B. Emulated instructions 1850 stored in memory 1804comprise software instructions (e.g., correlating to machineinstructions) that were developed to be executed in an architectureother than that of native CPU 1802. For example, emulated instructions1850 may have been designed to execute on a z/Architecture processor,but instead, are being emulated on native CPU 1802, which may be, forexample, an Intel Itanium II processor. In one example, emulator code1812 includes an instruction fetching routine 1852 to obtain one or moreemulated instructions 1850 from memory 1804, and to optionally providelocal buffering for the instructions obtained. It also includes aninstruction translation routine 1854 to determine the type of emulatedinstruction that has been obtained and to translate the emulatedinstruction into one or more corresponding native instructions 1856.This translation includes, for instance, identifying the function to beperformed by the emulated instruction and choosing the nativeinstruction(s) to perform that function.

Further, emulator code 1812 includes an emulation control routine 1860to cause the native instructions to be executed. Emulation controlroutine 1860 may cause native CPU 1802 to execute a routine of nativeinstructions that emulate one or more previously obtained emulatedinstructions and, at the conclusion of such execution, return control tothe instruction fetch routine to emulate the obtaining of the nextemulated instruction or a group of emulated instructions. Execution ofthe native instructions 1856 may include loading data into a registerfrom memory 1804; storing data back to memory from a register; orperforming some type of arithmetic or logic operation, as determined bythe translation routine.

Each routine is, for instance, implemented in software, which is storedin memory and executed by native central processing unit 1802. In otherexamples, one or more of the routines or operations are implemented infirmware, hardware, software or some combination thereof. The registersof the emulated processor may be emulated using registers 1810 of thenative CPU or by using locations in memory 1804. In embodiments,emulated instructions 1850, native instructions 1856 and emulator code1812 may reside in the same memory or may be disbursed among differentmemory devices.

As used herein, firmware includes, e.g., the microcode, millicode and/ormacrocode of the processor. It includes, for instance, thehardware-level instructions and/or data structures used inimplementation of higher level machine code. In one embodiment, itincludes, for instance, proprietary code that is typically delivered asmicrocode that includes trusted software or microcode specific to theunderlying hardware and controls operating system access to the systemhardware.

Moreover, one or more aspects may relate to cloud computing.

It is understood in advance that although this disclosure includes adetailed description on cloud computing, implementation of the teachingsrecited herein are not limited to a cloud computing environment. Rather,embodiments of the present invention are capable of being implemented inconjunction with any other type of computing environment now known orlater developed.

Cloud computing is a model of service delivery for enabling convenient,on-demand network access to a shared pool of configurable computingresources (e.g. networks, network bandwidth, servers, processing,memory, storage, applications, virtual machines, and services) that canbe rapidly provisioned and released with minimal management effort orinteraction with a provider of the service. This cloud model may includeat least five characteristics, at least three service models, and atleast four deployment models.

Characteristics are as follows:

On-demand self-service: a cloud consumer can unilaterally provisioncomputing capabilities, such as server time and network storage, asneeded automatically without requiring human interaction with theservice's provider.

Broad network access: capabilities are available over a network andaccessed through standard mechanisms that promote use by heterogeneousthin or thick client platforms (e.g., mobile phones, laptops, and PDAs).

Resource pooling: the provider's computing resources are pooled to servemultiple consumers using a multi-tenant model, with different physicaland virtual resources dynamically assigned and reassigned according todemand. There is a sense of location independence in that the consumergenerally has no control or knowledge over the exact location of theprovided resources but may be able to specify location at a higher levelof abstraction (e.g., country, state, or datacenter).

Rapid elasticity: capabilities can be rapidly and elasticallyprovisioned, in some cases automatically, to quickly scale out andrapidly released to quickly scale in. To the consumer, the capabilitiesavailable for provisioning often appear to be unlimited and can bepurchased in any quantity at any time.

Measured service: cloud systems automatically control and optimizeresource use by leveraging a metering capability at some level ofabstraction appropriate to the type of service (e.g., storage,processing, bandwidth, and active user accounts). Resource usage can bemonitored, controlled, and reported providing transparency for both theprovider and consumer of the utilized service.

Service Models are as follows:

Software as a Service (SaaS): the capability provided to the consumer isto use the provider's applications running on a cloud infrastructure.The applications are accessible from various client devices through athin client interface such as a web browser (e.g., web-based email). Theconsumer does not manage or control the underlying cloud infrastructureincluding network, servers, operating systems, storage, or evenindividual application capabilities, with the possible exception oflimited user-specific application configuration settings.

Platform as a Service (PaaS): the capability provided to the consumer isto deploy onto the cloud infrastructure consumer-created or acquiredapplications created using programming languages and tools supported bythe provider. The consumer does not manage or control the underlyingcloud infrastructure including networks, servers, operating systems, orstorage, but has control over the deployed applications and possiblyapplication hosting environment configurations.

Infrastructure as a Service (IaaS): the capability provided to theconsumer is to provision processing, storage, networks, and otherfundamental computing resources where the consumer is able to deploy andrun arbitrary software, which can include operating systems andapplications. The consumer does not manage or control the underlyingcloud infrastructure but has control over operating systems, storage,deployed applications, and possibly limited control of select networkingcomponents (e.g., host firewalls).

Deployment Models are as follows:

Private cloud: the cloud infrastructure is operated solely for anorganization. It may be managed by the organization or a third party andmay exist on-premises or off-premises.

Community cloud: the cloud infrastructure is shared by severalorganizations and supports a specific community that has shared concerns(e.g., mission, security requirements, policy, and complianceconsiderations). It may be managed by the organizations or a third partyand may exist on-premises or off-premises.

Public cloud: the cloud infrastructure is made available to the generalpublic or a large industry group and is owned by an organization sellingcloud services.

Hybrid cloud: the cloud infrastructure is a composition of two or moreclouds (private, community, or public) that remain unique entities butare bound together by standardized or proprietary technology thatenables data and application portability (e.g., cloud bursting forloadbalancing between clouds).

A cloud computing environment is service oriented with a focus onstatelessness, low coupling, modularity, and semantic interoperability.At the heart of cloud computing is an infrastructure comprising anetwork of interconnected nodes.

Referring now to FIG. 19, a schematic of an example of a cloud computingnode is shown. Cloud computing node 10 is only one example of a suitablecloud computing node and is not intended to suggest any limitation as tothe scope of use or functionality of embodiments of the inventiondescribed herein. Regardless, cloud computing node 10 is capable ofbeing implemented and/or performing any of the functionality set forthhereinabove.

In cloud computing node 10 there is a computer system/server 12, whichis operational with numerous other general purpose or special purposecomputing system environments or configurations. Examples of well-knowncomputing systems, environments, and/or configurations that may besuitable for use with computer system/server 12 include, but are notlimited to, personal computer systems, server computer systems, thinclients, thick clients, handheld or laptop devices, multiprocessorsystems, microprocessor-based systems, set top boxes, programmableconsumer electronics, network PCs, minicomputer systems, mainframecomputer systems, and distributed cloud computing environments thatinclude any of the above systems or devices, and the like.

Computer system/server 12 may be described in the general context ofcomputer system-executable instructions, such as program modules, beingexecuted by a computer system. Generally, program modules may includeroutines, programs, objects, components, logic, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Computer system/server 12 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in FIG. 19, computer system/server 12 in cloud computing node10 is shown in the form of a general-purpose computing device. Thecomponents of computer system/server 12 may include, but are not limitedto, one or more processors or processing units 16, a system memory 28,and a bus 18 that couples various system components including systemmemory 28 to processor 16.

Bus 18 represents one or more of any of several types of bus structures,including a memory bus or memory controller, a peripheral bus, anaccelerated graphics port, and a processor or local bus using any of avariety of bus architectures. By way of example, and not limitation,such architectures include Industry Standard Architecture (ISA) bus,Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, VideoElectronics Standards Association (VESA) local bus, and PeripheralComponent Interconnect (PCI) bus.

Computer system/server 12 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 12, and it includes both volatileand non-volatile media, removable and non-removable media.

System memory 28 can include computer system readable media in the formof volatile memory, such as random access memory (RAM) 30 and/or cachememory 32. Computer system/server 12 may further include otherremovable/non-removable, volatile/non-volatile computer system storagemedia. By way of example only, storage system 34 can be provided forreading from and writing to a non-removable, non-volatile magnetic media(not shown and typically called a “hard drive”). Although not shown, amagnetic disk drive for reading from and writing to a removable,non-volatile magnetic disk (e.g., a “floppy disk”), and an optical diskdrive for reading from or writing to a removable, non-volatile opticaldisk such as a CD-ROM, DVD-ROM or other optical media can be provided.In such instances, each can be connected to bus 18 by one or more datamedia interfaces. As will be further depicted and described below,memory 28 may include at least one program product having a set (e.g.,at least one) of program modules that are configured to carry out thefunctions of embodiments of the invention.

Program/utility 40, having a set (at least one) of program modules 42,may be stored in memory 28 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. Program modules 42 generally carry out the functions and/ormethodologies of embodiments of the invention as described herein.

Computer system/server 12 may also communicate with one or more externaldevices 14 such as a keyboard, a pointing device, a display 24, etc.;one or more devices that enable a user to interact with computersystem/server 12; and/or any devices (e.g., network card, modem, etc.)that enable computer system/server 12 to communicate with one or moreother computing devices. Such communication can occur via Input/Output(I/O) interfaces 22. Still yet, computer system/server 12 cancommunicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 20. As depicted, network adapter 20communicates with the other components of computer system/server 12 viabus 18. It should be understood that although not shown, other hardwareand/or software components could be used in conjunction with computersystem/server 12. Examples, include, but are not limited to: microcode,device drivers, redundant processing units, external disk drive arrays,RAID systems, tape drives, and data archival storage systems, etc.

Referring now to FIG. 20, illustrative cloud computing environment 50 isdepicted. As shown, cloud computing environment 50 comprises one or morecloud computing nodes 10 with which local computing devices used bycloud consumers, such as, for example, personal digital assistant (PDA)or cellular telephone 54A, desktop computer 54B, laptop computer 54C,and/or automobile computer system 54N may communicate. Nodes 10 maycommunicate with one another. They may be grouped (not shown) physicallyor virtually, in one or more networks, such as Private, Community,Public, or Hybrid clouds as described hereinabove, or a combinationthereof. This allows cloud computing environment 50 to offerinfrastructure, platforms and/or software as services for which a cloudconsumer does not need to maintain resources on a local computingdevice. It is understood that the types of computing devices 54A-N shownin FIG. 20 are intended to be illustrative only and that computing nodes10 and cloud computing environment 50 can communicate with any type ofcomputerized device over any type of network and/or network addressableconnection (e.g., using a web browser).

Referring now to FIG. 21, a set of functional abstraction layersprovided by cloud computing environment 50 (FIG. 20) is shown. It shouldbe understood in advance that the components, layers, and functionsshown in FIG. 21 are intended to be illustrative only and embodiments ofthe invention are not limited thereto. As depicted, the following layersand corresponding functions are provided:

Hardware and software layer 60 includes hardware and softwarecomponents. Examples of hardware components include mainframes 61; RISC(Reduced Instruction Set Computer) architecture based servers 62;servers 63; blade servers 64; storage devices 65; and networks andnetworking components 66. In some embodiments, software componentsinclude network application server software 67 and database software 68.

Virtualization layer 70 provides an abstraction layer from which thefollowing examples of virtual entities may be provided: virtual servers71; virtual storage 72; virtual networks 73, including virtual privatenetworks; virtual applications and operating systems 74; and virtualclients 75.

In one example, management layer 80 may provide the functions describedbelow. Resource provisioning 81 provides dynamic procurement ofcomputing resources and other resources that are utilized to performtasks within the cloud computing environment. Metering and Pricing 82provide cost tracking as resources are utilized within the cloudcomputing environment, and billing or invoicing for consumption of theseresources. In one example, these resources may comprise applicationsoftware licenses. Security provides identity verification for cloudconsumers and tasks, as well as protection for data and other resources.User portal 83 provides access to the cloud computing environment forconsumers and system administrators. Service level management 84provides cloud computing resource allocation and management such thatrequired service levels are met. Service Level Agreement (SLA) planningand fulfillment 85 provide pre-arrangement for, and procurement of,cloud computing resources for which a future requirement is anticipatedin accordance with an SLA.

Workloads layer 90 provides examples of functionality for which thecloud computing environment may be utilized. Examples of workloads andfunctions which may be provided from this layer include: mapping andnavigation 91; software development and lifecycle management 92; virtualclassroom education delivery 93; data analytics processing 94;transaction processing 95; and short pointer mode execution processing96.

The present invention may be a system, a method, and/or a computerprogram product at any possible technical detail level of integration.The computer program product may include a computer readable storagemedium (or media) having computer readable program instructions thereonfor causing a processor to carry out aspects of the present invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, configuration data for integrated circuitry, oreither source code or object code written in any combination of one ormore programming languages, including an object oriented programminglanguage such as Smalltalk, C++, or the like, and procedural programminglanguages, such as the “C” programming language or similar programminglanguages. The computer readable program instructions may executeentirely on the user's computer, partly on the user's computer, as astand-alone software package, partly on the user's computer and partlyon a remote computer or entirely on the remote computer or server. Inthe latter scenario, the remote computer may be connected to the user'scomputer through any type of network, including a local area network(LAN) or a wide area network (WAN), or the connection may be made to anexternal computer (for example, through the Internet using an InternetService Provider). In some embodiments, electronic circuitry including,for example, programmable logic circuitry, field-programmable gatearrays (FPGA), or programmable logic arrays (PLA) may execute thecomputer readable program instructions by utilizing state information ofthe computer readable program instructions to personalize the electroniccircuitry, in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

In addition to the above, one or more aspects may be provided, offered,deployed, managed, serviced, etc. by a service provider who offersmanagement of customer environments. For instance, the service providercan create, maintain, support, etc. computer code and/or a computerinfrastructure that performs one or more aspects for one or morecustomers. In return, the service provider may receive payment from thecustomer under a subscription and/or fee agreement, as examples.Additionally or alternatively, the service provider may receive paymentfrom the sale of advertising content to one or more third parties.

In one aspect, an application may be deployed for performing one or moreembodiments. As one example, the deploying of an application comprisesproviding computer infrastructure operable to perform one or moreembodiments.

As a further aspect, a computing infrastructure may be deployedcomprising integrating computer readable code into a computing system,in which the code in combination with the computing system is capable ofperforming one or more embodiments.

As yet a further aspect, a process for integrating computinginfrastructure comprising integrating computer readable code into acomputer system may be provided. The computer system comprises acomputer readable medium, in which the computer medium comprises one ormore embodiments. The code in combination with the computer system iscapable of performing one or more embodiments.

Although various embodiments are described above, these are onlyexamples. For example, computing environments of other architectures canbe used to incorporate and use one or more embodiments. Further,different instructions, instruction formats, instruction fields and/orinstruction values may be used. Many variations are possible.

Further, other types of computing environments can benefit and be used.As an example, a data processing system suitable for storing and/orexecuting program code is usable that includes at least two processorscoupled directly or indirectly to memory elements through a system bus.The memory elements include, for instance, local memory employed duringactual execution of the program code, bulk storage, and cache memorywhich provide temporary storage of at least some program code in orderto reduce the number of times code must be retrieved from bulk storageduring execution.

Input/Output or I/O devices (including, but not limited to, keyboards,displays, pointing devices, DASD, tape, CDs, DVDs, thumb drives andother memory media, etc.) can be coupled to the system either directlyor through intervening I/O controllers. Network adapters may also becoupled to the system to enable the data processing system to becomecoupled to other data processing systems or remote printers or storagedevices through intervening private or public networks. Modems, cablemodems, and Ethernet cards are just a few of the available types ofnetwork adapters.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a”, “an” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. It willbe further understood that the terms “comprises” and/or “comprising”,when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below, if any, areintended to include any structure, material, or act for performing thefunction in combination with other claimed elements as specificallyclaimed. The description of one or more embodiments has been presentedfor purposes of illustration and description, but is not intended to beexhaustive or limited to in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the art. Theembodiment was chosen and described in order to best explain variousaspects and the practical application, and to enable others of ordinaryskill in the art to understand various embodiments with variousmodifications as are suited to the particular use contemplated.

What is claimed is:
 1. A computer program product for facilitatingprocessing in a computing environment, said computer program productcomprising: a non-transitory computer readable storage medium readableby a processing circuit and storing instructions for execution by theprocessing circuit for performing a method comprising: determining thata short pointer mode application has been loaded; reconfiguring, basedon determining the short pointer mode application has been loaded, anaddress space configured for a long pointer mode environment, theaddress space having one portion addressable by short pointers of adefined size and another portion addressable by long pointers of anotherdefined size, the reconfiguring comprising: obtaining a long pointerlibrary; and loading the long pointer library in the one portion of theaddress space addressable by short pointers; obtaining a select libraryto load; loading the select library in the one portion of the addressspace or the other portion of the address space, based on the selectlibrary not being a short pointer library; and modifying by the selectlibrary one or more characteristics of the select library for the selectlibrary to be operable in a short mode environment.
 2. The computerprogram product of claim 1, wherein the short pointer mode applicationis loaded in the one portion of the address space addressable by shortpointers.
 3. The computer program product of claim 1, wherein thereconfiguring further comprises configuring a stack in the one portionof the address space addressable by short pointers.
 4. The computerprogram product of claim 1, wherein the reconfiguring further comprisesconfiguring a heap in the one portion of the address space addressableby short pointers.
 5. The computer program product of claim 1, whereinthe method further comprises: determining whether the select library isa short pointer library; and loading the select library in the oneportion of the address space addressable by short pointers, based on theselect library being a short pointer library.
 6. The computer programproduct of claim 5, wherein the method further comprises loading theselect library in the other portion of the address space, based on theselect library not being a short pointer library.
 7. The computerprogram product of claim 1, wherein the defined size is one of 31 bitsor 32 bits, and the other defined size is 64 bits.
 8. The computerprogram product of claim 1, wherein the determining includes checking afield associated with the application.
 9. The computer program productof claim 1, wherein a pointer of the long pointer library is a procedurelinkage table pointer, and the procedure linkage table pointer is a longpointer.
 10. A computer system for facilitating processing in acomputing environment, said computer system comprising: a memory; and aprocessor in communication with the memory, wherein the computer systemis configured to perform a method, said method comprising: determiningthat a short pointer mode application has been loaded; andreconfiguring, based on determining the short pointer mode applicationhas been loaded, an address space configured for a long pointer modeenvironment, the address space having one portion addressable by shortpointers of a defined size and another portion addressable by longpointers of another defined size, the reconfiguring comprising:obtaining a long pointer library; and loading the long pointer libraryin the one portion of the address space addressable by short pointers;obtaining a select library to load; loading the select library in theone portion of the address space or the other portion of the addressspace, based on the select library not being a short pointer library;and modifying by the select library one or more characteristics of theselect library for the select library to be operable in a short modeenvironment.
 11. The computer system of claim 10, wherein the shortpointer mode application is loaded in the one portion of the addressspace addressable by short pointers.
 12. The computer system of claim10, wherein the reconfiguring further comprises configuring a stack inthe one portion of the address space addressable by short pointers. 13.The computer system of claim 10, wherein the reconfiguring furthercomprises configuring a heap in the one portion of the address spaceaddressable by short pointers.
 14. A computer-implemented method offacilitating processing in a computing environment, saidcomputer-implemented method comprising: determining, by a processor,that a short pointer mode application has been loaded; andreconfiguring, based on determining the short pointer mode applicationhas been loaded, an address space configured for a long pointer modeenvironment, the address space having one portion addressable by shortpointers of a defined size and another portion addressable by longpointers of another defined size, the reconfiguring comprising:obtaining a long pointer library; and loading the long pointer libraryin the one portion of the address space addressable by short pointers;obtaining a select library to load; loading the select library in theone portion of the address space or the other portion of the addressspace, based on the select library not being a short pointer library;and modifying by the select library one or more characteristics of theselect library for the select library to be operable in a short modeenvironment.
 15. The computer-implemented method of claim 14, whereinthe short pointer mode application is loaded in the one portion of theaddress space addressable by short pointers.
 16. Thecomputer-implemented method of claim 14, wherein the reconfiguringfurther comprises configuring a stack in the one portion of the addressspace addressable by short pointers.
 17. The computer-implemented methodof claim 14, wherein the reconfiguring further comprises configuring aheap in the one portion of the address space addressable by shortpointers.